"Yes. But how—"
"Oh, I only guessed it," said Keen with a smile. "I made another guess that your case involved a cipher code. Does it?"
"Y-es," said the young man, astonished, "but I don't see—"
"It also involves the occult," observed Keen calmly. "We may need Miss Borrow to help us."
Almost staggered, Harren stared at the Tracer out of his astonished gray eyes until that gentleman laughed outright and seated himself, motioning Harren to do likewise.
"Don't be surprised, Captain Harren," he said. "I suppose you have no conception of our business, no realization of its scope—its network of information bureaus all over the civilized world, its myriad sources of information, the immensity of its delicate machinery, the endless data and the infinitesimal details we have at our command. You, of course, have no idea of the number of people of every sort and condition who are in our employ, of the ceaseless yet inoffensive surveillance we maintain. For example, when your letter came last week I called up the person who has charge of the army list. There you were, Kenneth Harren, Captain Philippine Scouts, with the date of your graduation from West Point. Then I called up a certain department devoted to personal detail, and in five minutes I knew your entire history. I then touched another electric button, and in a minute I had before me the date of your arrival in New York, your present address, and"—he looked up quizzically at Harren—"and several items of general information, such as your peculiar use of your camera, and the list of books on Psychical Phenomena and Cryptograms which you have been buying—"
Harren flushed up. "Do you mean to say that I have been spied upon, Mr. Keen?"
"No more than anybody else who comes to us as a client. There was nothing offensive in the surveillance." He shrugged his shoulders and made a deprecating gesture. "Ours is a business, my dear sir, like any other. We, of course, are obliged to know about people who call on us. Last week you wrote me, and I immediately set every wheel in motion; in other words, I had you under observation from the day I received your letter to this very moment."
"You learned much concerning me?" asked Harren quietly.
"Exactly, my dear sir."